Switch mechanism for starting electric motors



J. EATON. SWITCH MECHANISM FOR STARTING ELECTRIC MOTORS.

APPLICATION FILED JAN. 15, I920.

Patented N 0V. 2, 1920 Inventor-I John Eaton His Attorney.

UNITED- STATES- PATENT OFFICE.

JOI-IN EATON, SCHENECTADY, NEW YORK, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SWITCH MECHANISM FOR STARTING ELECTRIC MOTORS.

Application filed January 15, 1920. SeriaiNo. 351,729;

. J To all whom it may concern:

Be it known that I, JOHN EATON, a subject of the King of Great Britain, residing at Schenectady, county of Schnectady, State of New York, have invented certain new and useful Improvements in Switch Mechani'sm for Starting Electric Motors, of which .the following is a specification.

My invention relates to an improved arrangement for starting electric motors, and is particularly adapted for use with alter- I nating current motors of the squirrel cage rotortype which arecontrolled by connecting them to a source of low voltagefor starting and then increasing the impressed voltage for running, but .my invention is I not limited to this particular type of motor.

The object of my invention is to provide an efficient and reliable automatic starter for electric motors by means of which motors may be controlled from a distance either manually or in res' onse to the operation of another device. y invention provides improved means whereby the motor is first connected to the source of supply through a low voltage connection, and after a predetermined interval the motor is automatically connected to the source of supply through a full voltage connection.

My invention relates to features of construction and arrangement which will be explained fully hereinafter and particularly pointed out in the claims.

1 For a better understanding of my invention, reference is had to the accompanying drawings which illustrate in diagrammatic form an embodiment of my invention, and

in which the electric motor M of the alternating current squirrel cage rotor type is adapted to be connected to the source of supply 10 through an intermediate low voltage connection of the auto-transformer 11 by means of the electromagnetic switch or contactor 12. The motor is adapted to be connected directly to the source of supply by means of the electromagnetic switch or contactor 13. The master switch for controlling these contactors comprises the starting push button switch 14 having two contact disks adapted to contact with their respective stationary contacts, the upper disk 15 and the lower disk 16 being connected together by means of the spring 17 which is compressed when the push button 1s depressed. The disks are mounted so as to Specification of Letters Patent.

Patented Nov. 2,1920.

ment of the push button will belittle more than the resistance ofi'ered by the spring 19. When pressure is released from the push button, the upper contact disk 15 will immediately break engagement with its corresponding contacts due to the compression of spring 17, but the lower contact 16 will not break engagement with its contacts until the collar 21 on the stem of the dash pot lifts the contact disk due to the piston of the dash potrising by reason of the force exerted by the spring 19. A resistor 22 is provided for reducing the current in the coil circuit of the electromagnet switch 12 when the push button 14 is released afterhaving been depressed. A pivoted mechanical interlock 23 is provided for preventingboth the contac'tors 12 and 13 being closed at the same time, and also for the purpose of estabhshing the circuit for the winding of contactor 13 when the contactor 12 closes.

engagement with its contacts at about the same time that the contact disk 15 makes engagement with its contacts, and causing the piston of the dash pot to be moved to its lower position against the bias of the spring 19. The winding of the electromagnet switch will thus be connected to the source of supply and the switch will close,

thereby cdnnecting the motor to thesource of supply through the reduced voltage tap of the auto-transformer 11. The motorwill start and by reason of the fact that it is supplied with current at a lower potential than full line potential, the current ta'ken will not bein excess of the proper value. As soon as the push button 14 is released, the contact disk 15 will break engagement with its contacts due to,the compression of the spring 17 and the winding. of the contactor 12 will be connected to the source of supply through the resistor 22, thereby maintaining the contactor closed with a relock 23 and the insulated tip 25 on the con,-

tactor 13. The contactor 13 will not close, however, until the contactor 12 is automatically opened through the operation of the dash pot, since'the pull of the winding of contactor 12 is sufiicient to hold this contactor closed despite the force tending to open the contactor exerted by the contactor 13 through the pivoted mechanical interlock 23. fter a predetermined interval, which is determined by the setting of the dash pot 18, the collar 21 will automatically lift the contact disk 16 and open the connection of the winding'of contactor 12 tothe source of supply. The contactor 12 will open and /contactor 13 will thereby be permitted to closeand connect the motor directly to the source. The motor can be stopped at any desired time by depressing the normally closed stop push button 26. f

In accordance with the provisions of the patent statutes, l have described the] principle of operation of my invention, togetherwith the apparatus which ll now consider to represent-the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative, and that the invention other means.

-What I claim as new and desire] to secure by Letters Patent of the United States, is;- 1. Means for controlling an electric motor, comprising two electromagnetic switches the first for causing the motor to .be supplie with current at one potential .and the secondfor causing the motor .to be supplied with current at a higher potental, a normally open master, switch temporarily closed to effect the closing of the first electromagnetic switch and then automatically returned to its initial open position after a predetermined interval of time,-an d means whereby the first electromagnetic switch is openedand the second is closed responsively tothe return of the master switchto its initial open position.

2. Means for controlling an electric motor, comprising two electromagnetic switches, the first for causing the motor toa'be supplied with a current at one potential and the second for causing the motor to be supplied with current at one potential and the manually operated normally open master 7 switch for said electromagnetic switches,

ter switch to its initial open .position a means for automatically returning the maspredetermined interval of time after it is closed, and connections whereby the first plied with current at one potential and the can be carried out by electromagnetic switch is energized to close in response to the closing of the master switch, and the first'electromagnetic switch is opened and the second is automatically closed responsively to the return of the master switch to its initial open position.

3. Means for controlling an electric motor, comprising two electromagnetic switches, the first for causing the motor to be supsecond for causing the motor to be supplied with current at a higher potential, a master switch'biased to its open position, means whereby the master switch is niovable quickly to the closed position against" its bias and is retarded in its return movement to the open position in accordance with its bias, and connections whereby the first electromagnetic switch is energized to close in response to the closing of the master switch, and .the first electromagnetic switch is opened and the second is automatically closed responsively to the returnof the master switch to its initial open position.

at. Means for controlling an electric motor, comprising two electromagnetic switches, the first for causing the'motor to be supplied withcurrent atone potential and the second for causing the motor to be supplied with current at a higher potential, aamaster i switch for said electromagnetic switches,-

means for automatically opening the master switch a predetermined interval of time after'it is closed, and "connections whereby the closing of the master switch energizes the first electromagnetic switch to close and thereby energize thewinding of the second electromagnetic switch, whereupon the deenergization of the winding of the first electromagnetic switch after a predetermined interval of time eflects the closing of the second electromagnetic switch.

5. Means for controlling an electric motor, comprising two electromagnetic switches, the first for causing the with current atone potential and the second for causing the motor to be supplied with r current at a higher potentiahan interlock for preventing both switches from being simultaneously closed, a master switch for said electromagnetic switches, means for automatically opening the master switch a predetermined time after it is closed, and connections whereby closing the masterswitch energizes the first electromagnetic switch to close and thereby energize the winding of the second electromagnetic switch through the said interlock, whereupon the denergization of the first electromotor to be supplied 110 with current at one potential and the.

push button switch and the winding of the second electromagnetic switch is thereby energized through the said mechanical interlock, whereupon the second electromagnetic switch is closed and first opened by the automatic opening of the push button switch after a predetermined interval of time.

In witness whereof I have hereunto set my hand this 13th day of January, 1920.

JOHN EATON. 

